This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This application for a clinical supplement to the Columbia Udall Center of Excellence for Parkinson's Disease Research represents a continuation of the work supported by the Center during the past funding period [P50 NS 38370, Project 5: "The Assessment of Disease Progression in Parkinsonism"]. As part of the Columbia Udall Center, Dr. Eidelberg with his colleagues developed and implemented a novel network imaging strategy to study brain-behavior relationships in Parkinson's disease (PD). The research utilized functional brain imaging with positron emission tomography (PET) in conjunction with on-line psychophysical recordings to: (1) assess of longitudinal changes in the activity of functional brain networks during the course of early stage PD;(2) characterize specific brain networks associated with learning and cognition as potential imaging markers of higher cortical functioning in PD and related disorders;(3) explore the relationship between network activity and independent PET assessments of dopaminergic functioning in health and disease;and (4) determine the effects of treatment on network activity and the relationship of network modulation to therapeutic outcome.